Tailored template engineering of MoSe2/N,P-doped carbon nanospheres with sandwiched carbon and few-layered MoSe2 shells for stable and high-rate storage of Na+/K+-ions

Abstract

Layered MoSe₂ with a large interlayer has been regarded as an attractive host for larger-sized Na⁺/K⁺ ions. Nevertheless, serious volume effects and aggregation trends upon cycling are still great challenges for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). Herein, MoSe₂/N,P-doped carbon nanospheres with double-shells of N-doped carbon and few-layered MoSe₂ nanosheets (MoSe₂/N,P–C@N–C⊂MoSe₂) are synthesized through a tailored template of metal–organic networks. This core–double-shell structure with strong coupling between MoSe₂ nanosheets and the sandwiched carbon shell is beneficial for exposing more active sites, ion channels and interfacial boundaries, facilitating the fast electron/ion transfer, as well as effectively buffering the volume effects, guaranteeing the structural stability. As expected, it exhibits superior rate performance (242.0 mA h g⁻¹ at 10.0 A g⁻¹) and ultralong cycling stability (238.7 mA h g⁻¹ at 5.0 A g⁻¹ for the 5000th cycle) for SIBs. As for PIBs, a stable capacity of 216.8 mA h g⁻¹ can be retained after 500 cycles at 1.0 A g⁻¹ and high capacity of 186.8 mA h g⁻¹ is delivered at 5.0 A g⁻¹ for the rate behavior. The superior high-rate capability and stable Na⁺/K⁺-ion storage capability are promoted by the higher capacitive contribution and enhanced ionic diffusion kinetics. This work will open the way for advanced electrode construction for host large-sized Na⁺/K⁺ ions in the field of large-scale energy storage.